Wireless energy transmission to remote devices and energy harvesting from ambient energy sources are topics that attracted increased attention in a variety of applications, such as in mobile communication, computation devices and microsensor technologies. Various devices convert kinetic, electromagnetic or thermal energy into electrical energy to power electronic circuits. For instance, energy harvesting and transmission systems based on transformation of acoustic vibrations into electrical energy are also increasingly being used.
However, various energy harvesting systems and related approaches have been challenging to implement in various applications. For instance, harvesting sufficient energy can be difficult, particularly where an energy source may be inconsistent, as may relate to the ability to efficiently communicate (send and/or receive) energy. For energy harvesting applications employing transducers, transducer area may be increased to increase communicated power. However, increasing transducer area can reduce the acceptable angle via which power can be communicated, which can in turn decrease communicated power. For instance, when the size of a transducer is larger than the acoustic wavelength, the transducer becomes highly directional and may be limited in sensitivity to waves directly radiating from the normal direction. While acoustic energy harvesting can be performed at low frequencies (e.g., in the kHz range) where the wavelength is typically comparable to or larger than the physical transducer size, such an approach can render it difficult to generate high power. These and other matters have presented challenges to energy transmission, for a variety of applications.